A hard disk drive is a data storage device that stores information in the form of magnetic particles on concentric circles called tracks on one or more rigid disks called platters. It consists of platters, read/write heads, and motors that spin the platters and position the heads. Hard drives store operating systems, software, and files and come in various capacities ranging from 10GB to multiple terabytes. Common interface types are IDE, SATA, and SCSI and hard drives can fail due to issues like no operating system, cable problems, or not being detected.